Abstract：
Bacillus thuringiensis (Bt) and Lysinibacillus sphaericus (Ls) are the most widely used microbial insecticides. Both encounter unfavorable environmental factors and pesticides in the field. Here, the responses of Bt and Ls spores to glutaraldehyde were characterized using Raman spectroscopy and differential interference contrast imaging at the single-cell level. Bt spores were more sensitive to glutaraldehyde than Ls spores under prolonged exposure: <1.0% of Bt spores were viable after 10 min of 0.5% (v/v) glutaraldehyde treatment, compared to ~ 20% of Ls spores. The Raman spectra of glutaraldehyde-treated Bt and Ls spores were almost identical to those of untreated spores; however, the germination process of individual spores was significantly altered. The time to onset of germination, the period of rapid Ca2+-2,6-pyridinedicarboxylic acid (CaDPA) release, and the period of cortex hydrolysis of treated Bt spores were significantly longer than those of untreated spores, with dodecylamine germination being particularly affected. Similarly, the germination of treated Ls spores was significantly prolonged, although the prolongation was less than that of Bt spores. Although the interiors of Bt and Ls spores were undamaged and CaDPA did not leak, proteins and structures involved in spore germination could be severely damaged, resulting in slower and significantly prolonged germination. This study provides insights into the impact of glutaraldehyde on bacterial spores at the single cell level and the variability in spore response to glutaraldehyde across species and populations.
摘要：
苏云金芽孢杆菌(Bt)和球形溶血芽孢杆菌(Ls)是最广泛使用的微生物杀虫剂。两者都在田间遇到不利的环境因素和农药。这里,在单细胞水平上使用拉曼光谱和微分干涉对比成像表征了Bt和Ls孢子对戊二醛的反应。Bt孢子对戊二醛比Ls孢子在长期暴露下更敏感：<1.0％的Bt孢子在0.5％（v/v）戊二醛处理10分钟后存活，与约20%的Ls孢子相比。戊二醛处理的Bt和Ls孢子的拉曼光谱与未处理的孢子几乎相同；然而，单个孢子的萌发过程显著改变。发芽开始的时间，Ca2+-2,6-吡啶二羧酸（CaDPA）快速释放的时期，处理后的Bt孢子的皮层水解时间明显长于未处理的孢子，十二胺发芽特别受影响。同样，处理的Ls孢子的萌发显着延长，尽管延长的时间小于Bt孢子。尽管Bt和Ls孢子的内部没有受损，CaDPA没有泄漏，参与孢子萌发的蛋白质和结构可能会受到严重破坏，导致较慢和显著延长发芽。这项研究提供了有关戊二醛在单细胞水平上对细菌孢子的影响以及跨物种和种群的孢子对戊二醛反应的变异性的见解。
